1. Field of the Invention
This invention relates to an image forming apparatus such as an electrophotographic copying apparatus or a recording apparatus. In particular, it relates to an image forming apparatus assuming a construction in which the apparatus body can be divided into upper and lower parts to facilitate the maintenance check-up, cleaning or repair of the apparatus, and further to such an image forming apparatus having a structure which permits a photosensitive medium and some or all of image forming means disposed thereabout to be removably mounted as a unit with respect to the apparatus body (hereinafter referred to as the process kit).
2. Description of the Prior Art
In an image forming apparatus such as, for example, an electrophotographic copying apparatus, it is necessary to carry out interchange of a photosensitive medium as an image bearing member, replenishment of developer, discarding of waste toner, cleaning of the charging wire or maintenance of a developing device, and almost all of these maintenance operations have been carried out by professional servicemen.
However, in a compact electrophotographic copying apparatus directed to personal use and which are increasing in number, the irregularity of the copy volume by the user is great and it becomes difficult for professional servicemen to carry out the maintenance work or the like.
AIso, in the conventional copying apparatus, maintenance work has been individually carried out with respect to individual apparatus components (units) which require maintenance or the like. For example, when it has been desired to carry out the maintenance of the photosensitive drum, the members proximate to the photosensitive drum have been temporarily retracted by the use of a retracting mechanism, whereafter the photosensitive drum has been removed from the apparatus to thereby achieve the purpose. At such time, it has sometimes happened that the photosensitive drum is damaged by the proximate members or is stained by the user's hand directly touching the drum, and there has arisen the necessity of placing the photosensitive drum on a table exclusively for use for maintenance after removing it from the apparatus, and then carrying out the maintenance.
Also, as regards the developing device, the surface of the developing roller has sometimes been liable to be damaged or foreign substances have been liable to mix with the developer in the developer storing container. Similarly damage has occured to the charger and the like, and this has often adversely affected the images after the termination of the maintenance and thus, the greatest possible care has been required during the operation of the apparatus.
Further, as regards the cleaner or the like, for example, in a copying apparatus the body of which is divided into upper and lower parts during the treatment of waste toner, the waste toner has scattered within the apparatus or it has been necessary to cover the cleaner with paper or the like in advance so that the scattered toner does not affect the other portion of the apparatus, and furthermore, in a copying apparatus wherein maintenance of the cleaner must be carried out with the cleaner removed from the apparatus body, a table exclusively for use for maintenance has been required.
In this connection, a copying apparatus construction has been proposed in which, for example, some or all of the photosensitive drum, the charger, the developing device, the cleaner unit, etc. are integrally made into a process kit which may be removably assembled to the copying apparatus body to thereby facilitate the maintenance.
That is, by adopting a construction in which the photosensitive and some or all of the image forming means disposed thereabout, for example, the charger, the developing device and the cleaner, are integrally made into a kit (unit within the unit) which may be mounted on a frame member removably mounted with respect to the apparatus body, the removal of the interior of the apparatus and accordingly the maintenance thereof becomes easy. In other words, if a construction is adopted in which the frame member including said kit is held, for example, in a sufficiently forwardly projected condition with respect to the apparatus body and if a construction is adopted in which the kit is readily removably mounted with respect to the frame member, the number of proximate members which may interfere with their neighborhood will be decreased and the degree of freedom in all directions will be increased and the special table exclusively for use for maintenance will become unnecessary and thus, there will be provided an apparatus which is free of the evils peculiar to the conventional apparatus and is better in operability.
On the other hand, there are some copying apparatuses the body of which is divided into upper and lower parts to enable the interior of the apparatus to be opened to facilitate the works such as maintenance check-up, cleaning and repair of the copying apparatus. In such apparatuses, the upper frame provided with an exposure mechanism, a charger, a photosensitive medium, a developing device, a cleaner, etc. is pivotally connected to the lower frame with one end of the upper frame as the fulcrum. When maintenance check-up or repair of the interior of the apparatus body is required, the upper frame may be widely opened upwardly with respect to the lower frame to open the interior of the apparatus, whereafter the necessary work may be carried out.
With the recent increasing tendency of the copying apparatus toward compactness, light weight and personal use, such apparatus construction is becoming widely adopted as being very effective to carry out maintenance and particularly, when the work resulting from the occurrence of paper jam within the copying apparatus or other maintenance check-up or repair is to be carried out, the upper frame may be inclined greatly, say, by about 20.degree., with respect to the lower frame (horizontal) to provide very good operability.
Now, as a specific means for making the process kit removably mountable to facilitate the maintenance, it would occur to mind to temporarily retract the members proximate to the process kit, such as the charger, the separating member, the guide member, the conveying member, etc. when required or to open the upper and lower frames by a certain necessary amount.
However, it is not preferable to combine the former means with the opening-closing mechanism for the upper and lower frames for copying with the work resulting from the occurrence of paper jam or other maintenance check-up or repair, and cumbersomeness results from the use of the former means itself with attendant increased cost. That is, when a member proximate to the process kit, for example, the charger, is temporarily retracted, there will arise problems regarding the connection between the charger and the high voltage input contact, the cord treatment or the mounting-dismounting of the charger itself, and the insurance of the position of the charger.
Also, in the case of the separating member, there will arise problems regarding the method of separate driving, the reproducibility of positional accuracy, the treatment of a separating belt if it is adopted, and the method of stretching the belt.
Similar problems will occur to the guide member and the conveying member. Temporarily retracting such members proximate to the process kit will complicate the retracting mechanism itself as the apparatus becomes more compact.
Furthermore, the aforementioned units must unavoidably be arranged more proximately to one another as the apparatus becomes more compact and in this point as well, the former means may be said to be practically difficult.
In contrast, the latter means can achieve the purpose relatively easily by a simple mechanism and in the same way as the method of copying with the occurrence of paper jam. Thus, the maintenance can be carried out relatively easily in a copying apparatus the body of which is divided into upper and lower parts and which permits the process kit to be removably mounted with respect to the apparatus body.
However, when the upper frame is opened for maintenance or the like, the upper frame is greatly inclined with respect to the lower frame (horizontal) and accordingly, the process kit installed within the upper frame is also greatly inclined with respect to the lower frame. If the process kit is separated with respect to the apparatus body with the upper frame thus greatly inclined with respect to the lower frame, toner may spill out of the waste toner container during discarding of the waste toner in the cleaner because the cleaner is greatly inclined, or it may be impossible to fully replenish the developer container with fresh developer because the container is greatly inclined when the developing device is to be supplied with developer, and further, the great inclination of the upper frame may make the operability very poor when said operation is performed.
In this manner, carrying out the maintenance with the upper frame or the process kit greatly inclined with respect to the lower frame leads to poor operability and reduced function of the copying apparatus, and improvements in this respect are desired.